Current Transducer LESR series
IP N = 6, 15, 25, 50 A
Ref: LESR 6-NP, LESR 15-NP, LESR 25-NP, LESR 50-NP
For the electronic measurement of current: DC, AC, pulsed..., with galvanic separation between
the primary and the secondary circuit.
Features
Applications
● Closed loop multi-range current transducer
● AC variable speed and servo motor drives
● Voltage output
● Static converters for DC motor drives
● Unipolar supply voltage
● Battery supplied applications
● Compact design for PCB mounting.
● Uninterruptible Power Supplies (UPS)
● Switched Mode Power Supplies (SMPS)
Advantages
● Power supplies for welding applications
● Very low offset drift
● Solar inverters.
● Very good du/dt immunity
● CASR footprint compatible
Standards
● Reference pin with two modes: Ref IN and Ref OUT
● IEC 61800-5-1: 2007
● Extended measuring range for unipolar measurement.
● IEC 62109-1: 2010
● IEC 62477-1: 2012
● UL 508:2013.
Application Domain
● Industrial.
N°97.O8.09.000.0, N°97.O8.15.000.0, N°97.O8.19.000.0, N°97.O8.25.000.0
19June2023/Version 7
LEM reserves the right to carry out modifications on its transducers,
in order to improve them.
Page 1/21
LEM International SA
Route du Nant-d’Avril, 152
1217 Meyrin
www.lem.com
LESR series
Absolute maximum ratings
Parameter
Symbol
Unit
Value
Maximum supply voltage
UC max
V
7
Maximum primary conductor temperature
TB max
°C
110
Maximum primary current
IP max
A
20 × IP N
UESD max
kV
4
Maximum electrostatic discharge voltage
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum ratings for extended periods may
degrade reliability.
UL 508: Ratings and assumptions of certification
File # E189713 Volume: 2 Section: 11
Standards
● USR indicated investigation to the Standard for Industrial Control Equipment UL 508 , Seventeenth Edition
● CNR indicated investigation to the Canadian Standard for Industrial Control Equipment CSA C22.2 No. 14-13., Eleventh
Edition.
Ratings
Parameter
Symbol
Primary involved potential
Unit
Value
V AC/DC
600
Max surrounding air temperature
TA
°C
105
Primary current
IP
A
According to series primary
currents
Secondary supply voltage
UC
V DC
5
Output voltage
Uout
V
0 ... 5
Conditions of acceptability
When installed in the end-use equipment, consideration shall be given to the following:
1 - These devices must be mounted in a suitable end-use enclosure.
2-T
he terminals have not been evaluated for field wiring.
3 - The LES, LESR, LKSR, LPSR, LXS and LXSR Series shall be used in a pollution degree 2 environment or better.
4-L
ow voltage circuits are intended to be powered by a circuit derived from an isolating source (such as a transformer, optical
isolator, limiting impedance or electro-mechanical relay) and having no direct connection back to the primary circuit (other than
through the grounding means).
5-T
hese devices are intended to be mounted on the printed wiring board of the end-use equipment (with a minimum CTI of 100).
6 - LES, LESR, LKSR and LPSR Series: based on results of temperature tests, in the end-use application, a maximum of 110 °C
cannot be exceeded on the primary jumper.
Marking
Only those products bearing the UL or UR Mark should be considered to be Listed or Recognized and covered under UL’s FollowUp Service. Always look for the Mark on the product.
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LEM International SA
Route du Nant-d’Avril, 152
1217 Meyrin
www.lem.com
LESR series
Insulation coordination
Parameter
Symbol
Unit
Value
RMS voltage for AC insulation test, 50 Hz, 1 min
Ud
kV
4.3
Impulse withstand voltage 1.2/50 μs
UNi
kV
8
Insulation resistance
RINS
GΩ
18
Partial discharge RMS test voltage (qm < 10 pC)
Ut
kV
1.65
Clearance (pri. - sec.)
dCI
mm
7.55
Creepage distance (pri. - sec.)
dCp
mm
7.55
-
-
V0
Case material
Comparative tracking index
CTI
Comment
Measured at 500 V DC
According to UL 94
600
Application example
System voltage
V
300
Reinforced insulation
according to IEC 61800-5-1
CAT III, PD2
Application example
System voltage
V
600
Basic insulation
according to IEC 61800-5-1
CAT III, PD2
Environmental and mechanical characteristics
Parameter
Ambient operating temperature
Ambient storage temperature
Mass
Symbol
Unit
Min
TA
°C
−40
105
TA st
°C
−55
125
m
g
Typ
Max
Comment
10
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LEM International SA
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1217 Meyrin
www.lem.com
LESR series
Electrical data LESR 6-NP
At TA = 25 °C, UC = +5 V, NP = 1 turn, RL = 10 kΩ internal reference, unless otherwise noted (see Definition of typical, minimum and
maximum values paragraph in page 8).
Parameter
Symbol
Unit
Primary nominal RMS current
IP N
A
Primary current, measuring range
IP M
A
Number of primary turns
NP
Supply voltage
UC
V
Current consumption
IC
mA
Reference voltage @ IP = 0 A
Uref
V
2.485
External reference voltage
UE ref
V
0.5
2.75
Output voltage
Uout
V
0.25
4.75
with UC = +5 V
Output voltage @ IP = 0 A
Uout
V
Electrical offset voltage
UO E
mV
−6.25
6.25
100 % tested Uout − Uref
Electrical offset current
referred to primary
IO E
mA
−60
60
100 % tested
Temperature coefficient of Uref
@ IP = 0 A
TCUref
ppm/K
±70
Internal reference
Temperature coefficient of Uout
@ IP = 0 A
TCUout
ppm/K
±14
ppm/K of 2.5 V
−40 °C … 105 °C
Nominal sensitivity
SN
mV/A
Sensitivity error
εS
%
TCS
ppm/K
εL
% of IP N
−0.1
0.1
Magnetic offset current (10 × IP N)
referred to primary
IO M
mA
−25
25
Noise voltage spectral density
100 … 100 kHz referred to primary
uno
µV/√Hz
Uno pp
mVpp
Delay time to 10 % of the final output
value for IP N step
tD 10
µs
0.3
RL = 1 kΩ, di/dt = 50 A/µs
Delay time to 90 % of the final output
value for IP N step
tD 90
µs
0.4
RL = 1 kΩ, di/dt = 50 A/µs
Frequency bandwidth (±1 dB)
BW
kHz
Total error
εtot
% of IP N
1.25
Total error @ TA = 85 °C (105 °C)
εtot
% of IP N
1.25 (1.5)
Error
ε
% of IP N
0.45
Error @ TA = 85 °C (105 °C)
ε
% of IP N
0.75 (1)
Temperature coefficient of S
Linearity error
Peak-to-peak noise voltage
DC … 10 kHz
DC … 100 kHz
DC … 1 MHz
Min
Typ
Max
Comment
Apply derating according to
figure 21
6
−20
20
1, 2, 3
4.75
5
18 +
5.25
I (mA)
N
P
S
20.5 +
2.5
I (mA)
N
P
S
2.515
NS = 2000 turns
Internal reference
Uref
104.2
−0.2
625 mV/IP N
0.2
100 % tested
±40
−40 °C … 105 °C
7
10.5
13.4
13.6
300
RL = 1 kΩ
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LEM International SA
Route du Nant-d’Avril, 152
1217 Meyrin
www.lem.com
LESR series
Electrical data LESR 15-NP
At TA = 25 °C, UC = +5 V, NP = 1 turn, RL = 10 kΩ internal reference, unless otherwise noted (see Definition of typical, minimum and
maximum values paragraph in page 8).
Parameter
Symbol
Unit
Primary nominal RMS current
IP N
A
Primary current, measuring range
IP M
A
Number of primary turns
NP
Supply voltage
UC
V
Current consumption
IC
mA
Reference voltage @ IP = 0 A
Uref
V
2.485
External reference voltage
UE ref
V
0.5
2.75
Output voltage
Uout
V
0.25
4.75
with UC = +5 V
Output voltage @ IP = 0 A
Uout
V
Electrical offset voltage
UO E
mV
−2.5
2.5
100 % tested Uout − Uref
Electrical offset current
referred to primary
IO E
mA
−60
60
100 % tested
Temperature coefficient of Uref
@ IP = 0 A
TCUref
ppm/K
±70
Internal reference
Temperature coefficient of Uout
@ IP = 0 A
TCUout
ppm/K
±6
ppm/K of 2.5 V
−40 °C … 105 °C
Nominal sensitivity
SN
mV/A
Sensitivity error
εS
%
TCS
ppm/K
εL
% of IP N
−0.1
0.1
Magnetic offset current (10 × IP N)
referred to primary
IO M
mA
−45
45
Noise voltage spectral density
100 … 100 kHz referred to primary
uno
µV/√Hz
Uno pp
mVpp
Delay time to 10 % of the final output
value for IP N step
tD 10
µs
0.3
RL = 1 kΩ, di/dt = 50 A/µs
Delay time to 90 % of the final output
value for IP N step
tD 90
µs
0.4
RL = 1 kΩ, di/dt = 50 A/µs
Frequency bandwidth (±3 dB)
BW
kHz
Total error
εtot
% of IP N
0.7
Total error @ TA = 85 °C (105 °C)
εtot
% of IP N
0.75 (1)
Error
ε
% of IP N
0.45
Error @ TA = 85 °C (105 °C)
ε
% of IP N
0.65 (0.75)
Temperature coefficient of S
Linearity error
Peak-to-peak noise voltage
DC … 10 kHz
DC … 100 kHz
DC … 1 MHz
Min
Typ
Max
Comment
Apply derating according to
figure 22
15
−51
51
1, 2, 3
4.75
5
18 +
5.25
I (mA)
N
P
20.5 +
S
2.5
I (mA)
N
P
S
2.515
NS = 2000 turns
Internal reference
Uref
41.67
625 mV/IP N
−0.2
0.2
100 % tested
±40
−40 °C … 105 °C
3.5
4.5
5.7
6.3
300
RL = 1 kΩ
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LEM reserves the right to carry out modifications on its transducers,
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LEM International SA
Route du Nant-d’Avril, 152
1217 Meyrin
www.lem.com
LESR series
Electrical data LESR 25-NP
At TA = 25 °C, UC = +5 V, NP = 1 turn, RL = 10 kΩ internal reference, unless otherwise noted (see Definition of typical, minimum and
maximum values paragraph in page 8).
Parameter
Symbol
Unit
Primary nominal RMS current
IP N
A
Primary current, measuring range
IP M
A
Number of primary turns
NP
Supply voltage
UC
V
Current consumption
IC
mA
Reference voltage @ IP = 0 A
Uref
V
2.485
External reference voltage
UE ref
V
0.5
2.75
Output voltage
Uout
V
0.25
4.75
with UC = +5 V
Output voltage @ IP = 0 A
Uout
V
Electrical offset voltage
UO E
mV
−1.5
1.5
100 % tested Uout − Uref
Electrical offset current
referred to primary
IO E
mA
−60
60
100 % tested
Temperature coefficient of Uref
@ IP = 0 A
TCUref
ppm/K
±70
Internal reference
Temperature coefficient of Uout
@ IP = 0 A
TCUout
ppm/K
±4
ppm/K of 2.5 V
−40 °C … 105 °C
Nominal sensitivity
SN
mV/A
Sensitivity error
εS
%
TCS
ppm/K
εS
% of IP N
−0.1
0.1
Magnetic offset current (10 × IP N)
referred to primary
IO M
mA
−60
60
Noise voltage spectral density
100 … 100 kHz referred to primary
uno
µV/√Hz
Uno pp
mVpp
Delay time to 10 % of the final output
value for IP N step
tD 10
µs
0.3
RL = 1 kΩ, di/dt = 50 A/µs
Delay time to 90 % of the final output
value for IP N step
tD 90
µs
0.4
RL = 1 kΩ, di/dt = 50 A/µs
Frequency bandwidth (±3 dB)
BW
kHz
Settling time
ts
ms
8
Total error
εtot
% of IP N
0.75
Total error @ TA = 85 °C (105 °C)
εtot
% of IP N
0.85 (0.9)
Error
ε
% of IP N
0.45
Error @ TA = 85 °C (105 °C)
ε
% of IP N
0.65 (0.75)
Temperature coefficient of S
Linearity error
Peak-to-peak noise voltage
DC … 10 kHz
DC … 100 kHz
DC … 1 MHz
Min
Typ
Max
Comment
Apply derating according to
figure 23
25
−85
85
1, 2, 3
4.75
5
18 +
5.25
I (mA)
N
P
S
2.5
20.5 +
I (mA)
N
P
S
2.515
NS = 2000 turns
Internal reference
Uref
25
−0.2
625 mV/IP N
0.2
100 % tested
±40
−40 °C … 105 °C
1.8
2.6
3.9
5.1
300
RL = 1 kΩ
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LEM International SA
Route du Nant-d’Avril, 152
1217 Meyrin
www.lem.com
LESR series
Electrical data LESR 50-NP
At TA = 25 °C, UC = +5 V, NP = 1 turn, RL = 10 kΩ internal reference, unless otherwise noted (see Definition of typical, minimum and
maximum values paragraph in page 8).
Parameter
Symbol
Unit
Primary nominal RMS current
IP N
A
Primary current, measuring range
IP M
A
Number of primary turns
NP
Supply voltage
UC
V
Current consumption
IC
mA
Reference voltage @ IP = 0 A
Uref
V
2.485
External reference voltage
UE ref
V
0.5
2.75
Output voltage
Uout
V
0.25
4.75
with UC = +5 V
Output voltage @ IP = 0 A
Uout
V
Electrical offset voltage
UO E
mV
−0.875
0.875
100 % tested Uout − Uref
Electrical offset current
referred to primary
IO E
mA
−70
70
100 % tested
Temperature coefficient of Uref
@ IP = 0 A
TCUref
ppm/K
±70
Internal reference
Temperature coefficient of Uout
@ IP = 0 A
TCUout
ppm/K
±3
ppm/K of 2.5 V
−40 °C … 105 °C
Nominal sensitivity
SN
mV/A
Sensitivity error
εS
%
TCS
ppm/K
εL
% of IP N
−0.1
0.1
Magnetic offset current (10 × IP N)
referred to primary
IO M
mA
−60
60
Noise voltage spectral density
100 … 100 kHz referred to primary
uno
µV/√Hz
Uno pp
mVpp
Delay time to 10 % of the final output
value for IP N step
tD 10
µs
0.3
RL = 1 kΩ, di/dt = 50 A/µs
Delay time to 90 % of the final output
value for IP N step
tD 90
µs
0.4
RL = 1 kΩ, di/dt = 50 A/µs
Frequency bandwidth (±3 dB)
BW
kHz
Total error
εtot
% of IP N
0.65
Total error @ TA = 85 °C (105 °C)
εtot
% of IP N
0.7 (0.8)
Error
ε
% of IP N
0.45
Error @ TA = 85 °C (105 °C)
ε
% of IP N
0.65 (0.75)
Temperature coefficient of S
Linearity error
Peak-to-peak noise voltage
DC … 10 kHz
DC … 100 kHz
DC … 1 MHz
Min
Typ
Max
Comment
Apply derating according to
figure 24
50
−150
150
1, 2, 3
4.75
5
18 +
5.25
I (mA)
N
P
S
2.5
20.5 +
I (mA)
N
P
S
2.515
NS = 1600 turns
Internal reference
Uref
12.5
−0.2
625 mV/IP N
0.2
100 % tested
±40
−40 °C … 105 °C
1.7
2.4
3.2
4.8
300
RL = 1 kΩ
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LESR series
Definition of typical, minimum and maximum values
Minimum and maximum values for specified limiting and safety conditions have to be understood as such as well as values shown
in “typical” graphs.
On the other hand, measured values are part of a statistical distribution that can be specified by an interval with upper and lower
limits and a probability for measured values to lie within this interval.
Unless otherwise stated (e.g. “100 % tested”), the LEM definition for such intervals designated with “min” and “max” is that the
probability for values of samples to lie in this interval is 99.73 %.
For a normal (Gaussian) distribution, this corresponds to an interval between −3 sigma and +3 sigma. If “typical” values are not
obviously mean or average values, those values are defined to delimit intervals with a probability of 68.27 %, corresponding to an
interval between −sigma and +sigma for a normal distribution.
Typical, maximal and minimal values are determined during the initial characterization of the product.
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1217 Meyrin
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LESR series
Typical performance characteristics LESR 6-NP
0.1
4
Rel. Sensitivity 20
Phase
2
10
0
0
−2
−10
−4
−20
−6
−30
−8
−40
0
−0.05
−0.1
−6
−10
1
10
6
I [A]
Phase [°]
Relative Sensitivity [dB]
P
Figure 1: Linearity error
2
3
10
4
−50
6
10
5
10
10
Frequency [Hz]
10
Figure 2: Frequency response
6
0.625
4
0.417
Uout− Uref (V)
Linearity Error [ % IP N ]
0.05
IP (A)
IP
Uout− Uref
2
0.208
0
0
100
200
300
t (µs)
400
500
Figure 3: Step delay time
10000
3.5
3.4
600
3.3
3.2
100
10
3.1
400
UP
Uout
Uref
200
3.0
2.9
Uout (V)
Primary Voltage UP (V)
uno (µV RMS/ Hz1/2)
1000
2.8
2.7
2.6
1
2.5
1
10
2
10
3
10
4
10
fc (Hz)
Figure 4: Noise voltage spectral density
5
10
6
10
7
10
2.4
20 kV/µs
0
0
1
2
3
t (µs)
4
5
6
2.3
7
2.2
8
Figure 5: du/dt
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LESR series
Typical performance characteristics LESR 15-NP
0.1
4
Rel. Sensitivity 20
Phase
2
10
0
0
−2
−10
−4
−20
−6
−30
−8
−40
0
−0.05
−0.1
−15
−10
1
10
15
I [A]
Phase [°]
Relative Sensitivity [dB]
Linearity Error [ % IP N ]
0.05
2
3
10
P
Figure 6: Linearity error
4
−50
6
10
5
10
10
Frequency [Hz]
10
Figure 7: Frequency response
15
0.625
0.417
Uout− Uref (V)
10
IP (A)
IP
Uout− Uref
5
0.208
0
0
100
200
300
t (µs)
400
500
Figure 8: Step delay time
10000
3.5
3.4
600
3.3
3.2
100
10
3.1
400
UP
Uout
Uref
200
3.0
2.9
Uout (V)
Primary Voltage UP (V)
uno (µV/Hz
1/2
)
1000
2.8
2.7
2.6
2.5
1
1
10
2
10
3
10
4
fc (Hz)
10
Figure 9: Noise voltage spectral density
5
10
6
10
2.4
20 kV/µs
0
0
1
2
3
t (µs)
4
5
6
2.3
7
2.2
8
Figure 10: du/dt
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LESR series
Typical performance characteristics LESR 25-NP
0.1
0
−0.05
−0.1
−25
2
10
0
0
−2
−10
−4
−20
−6
−30
−8
−40
−10
1
10
25
IP [A]
Rel. Sensitivity 20
Phase
Phase [°]
Relative Sensitivity [dB]
Figure 11: Linearity error
2
3
10
4
−50
6
10
5
10
10
Frequency [Hz]
10
Figure 12: Frequency response
30
0.750
25
0.625
20
0.500
15
0.375
IP (A)
IP
Uout− Uref
10
0.250
5
0.125
0
0
100
200
300
t (µs)
400
500
Uout− Uref (V)
Linearity Error [ % IP N ]
0.05
4
600
Figure 13: Step delay time
3.5
10000
3.4
600
3.3
3.2
100
10
3.1
400
UP
Uout
Uref
200
3.0
2.9
2.8
Uout (V)
Primary Voltage UP (V)
uno (µV RMS/ Hz1/2 )
1000
2.7
2.6
1
2.5
1
10
2
10
3
10
4
fc (Hz)
10
Figure 14: Noise voltage spectral density
5
10
6
10
2.4
20 kV/µs
0
0
1
2
3
t (µs)
4
5
6
2.3
7
2.2
8
Figure 15: du/dt
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LESR series
Typical performance characteristics LESR 50-NP
0.1
Rel. Sensitivity 20
Phase
2
10
0
0
−2
−10
−4
−20
−6
−30
−8
−40
−0.05
−0.1
−50
−10
1
10
50
IP [A]
Phase [°]
0
Figure 16: Linearity error
2
3
10
4
−50
6
10
5
10
10
Frequency [Hz]
10
Figure 17: Frequency response
30
0.750
25
0.625
20
0.500
15
IP (A)
IP
Uout− Uref
10
0.375
0.250
5
0.125
0
0
100
200
300
t (µs)
400
Uout− Uref (V)
Linearity Error [ % I
PN
Relative Sensitivity [dB]
]
0.05
4
500
Figure 18: Step delay time
10000
3.5
3.4
600
3.3
3.2
100
10
3.1
400
UP
Uout
Uref
200
3.0
2.9
2.8
Uout (V)
Primary Voltage UP (V)
uno (µV RMS/ Hz1/2 )
1000
2.7
2.6
2.5
1
1
10
2
10
3
10
4
fc (Hz)
10
Figure 19: Noise voltage spectral density
5
10
6
10
2.4
20 kV/µs
0
0
1
2
3
t (µs)
4
5
6
2.3
7
2.2
8
Figure 20: du/dt
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LESR series
Maximum continuous DC primary current
100
40
90
35
80
30
70
60
IP (A)
IP (A)
25
20
40
15
30
10
20
5
10
0
0
20
40
60
80
TA (°C)
100
120
0
140
20
40
60
80
TA (°C)
100
120
140
100
120
140
160
100
90
140
80
120
70
100
IP (A)
60
IP (A)
0
Figure 22: IP vs TA for LESR 15-NP
Figure 21: IP vs TA for LESR 6-NP
50
40
80
60
30
40
20
20
10
0
50
0
20
40
60
80
TA (°C)
100
120
0
140
Figure 23: IP vs TA for LESR 25-NP
0
20
40
60
80
TA (°C)
Figure 24: IP vs TA for LESR 50-NP
The maximum continuous DC primary current plot shows the boundary of the area for which all the following conditions are true:
- IP < IP M
- Junction temperature TJ < 125 °C
- Primary conductor temperature < 110 °C
- Max power dissipation of internal resistors < 0.5 × resistors nominal power.
Frequency derating
Ip AC derating
max AC RMS current / max DC RMS current
1.33
1
0.66
0.33
0
10
100
1k
fc (Hz)
10k
100k
1M
Figure 25: Maximum RMS AC primary current / maximum DC primary current vs frequency
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LESR series
Performance parameters definition
Ampere-turns and amperes
Electrical offset
The transducer is sensitive to the primary current linkage ΘP
(also called ampere-turns).
ΘP = NP·IP (At)
Where NP is the number of primary turn (depending on
the connection of the primary jumpers)
Caution: As most applications will use the transducer with
only one single primary turn (NP = 1), much of this datasheet is
written in terms of primary current instead of current linkages.
However, the ampere-turns (At) unit is used to emphasis that
current linkages are intended and applicable.
Simplified transducer model
The electrical offset voltage UO E can either be measured when
the ferro-magnetic parts of the transducer are:
● Completely demagnetized, which is difficult to realize,
● or in a known magnetization state, like in the current cycle
shown in figure 27.
Using the current cycle shown in figure 27, the electrical offset
is:
UO E =
Uout (t1) + Uout (t2)
2
The temperature variation UO T of the electrical offset voltage
The static model of the transducer at temperature TA is:
Uout = S·ΘP + ε
In which ε =
UO E is the variation of the electrical offset from 25 °C to the
considered temperature:
UO T (T) = UO E (T) − UO E (25 °C)
UO E + UO T (TA) + εS ·ΘP·S + εL (ΘP max)·ΘP max·S + TCS·(TA−25)·ΘP·S
With: ΘP = NP·IP : primary current linkage (At)
ΘP max
: max primary current linkage applied to
the transducer
Note: the transducer has to be demagnetized prior to
the application of the current cycle (for example with a
demagnetization tunnel).
Uout : Output voltage (V)
TA
: ambient operating temperature (°C)
UO E
: electrical offset voltage (V)
UO T (TA)
: temperature variation of UO at
temperature TA (°C)
S
: sensitivity of the transducer (V/At)
TCS
: temperature coefficient of S
εS
: sensitivity error
εL(ΘP max) : linearity error for ΘP max
This model is valid for primary ampere-turns ΘP between
−ΘP max and +ΘP max only.
Total error
The total error at 25 °C εtot is the error in the −IP N … +IP N range,
relative to the rated value IP N.
It includes:
+UC
RL
Uref
Figure 26: Test connection
Magnetic offset
+UC
The magnetic offset current IO M is the consequence of a current
on the primary side (“memory effect” of
the
transducer’s
R
U
R
ferromagnetic parts).
It is measured using the following primary
U
current cycle. IO M depends on the current value IP1 (IP1 > IP M).
out
f
M
Cf
ref
IO M =
● the electrical offset UO E
● the sensitivity error εS
● the linearity error εL (to IP N)
Uout
RM
Uout(t1) − Uout(t2) 1
·
2
SN
IP (DC)
IP N
0A
−IP1 t
t2
t1
Ip(3)
Ip(t
3)
Figure 27: C
urrent cycle used to measure magnetic and
electrical offset (transducer supplied)
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LESR series
Performance parameters definition
Sensitivity and linearity
To measure sensitivity and linearity, the primary current (DC)
is cycled from 0 to IP, then to −IP and back to 0 (equally spaced
IP/10 steps). The sensitivity S is defined as the slope of the linear
regression line for a cycle between ±IP N.
The linearity error εL is the maximum positive or negative
difference between the measured points and the linear
regression line, expressed in % of IP N.
Delay times
The delay time tD 10 @ 10 % and the delay time tD 90 @ 90 % are
shown in figure 28.
Both depend on the primary current di/dt. They are measured at
nominal ampere-turns.
I
100 %
90 %
Uout
IP
tD 90
10 %
tD 10
t
Figure 28: tD 10 (delay time @ 10 %) and tD 90 (delay time @ 90 %)
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LESR series
Application information
Filtering and decoupling
Reference Uref
+UC
Like the output UoutR, the Uref has a very low output
impedance of
U
typically 1 Ohm; it can drive capacitive loads
R to 100 nF
U of up
directly. Adding series resistance Rf of several tenths of Ohms
allows much larger capacitive loads Cf (higher than 1 µF).
Empirical evaluation may be necessary to obtain optimum results.
The minimum load resistance on Uref is 10 kOhms.
Supply voltage UC
M
out
L
ref
The transducer has internal decoupling capacitors, but in
the case of a power supply with high impedance, it is highly
recommended to provide local decoupling (100 nF or more,
located close to the transducer) as it may reduce disturbance
on transducer output Uout and reference Uref due to high varying
primary current. The transducer power supply rejection ratio is
low at high frequency.
+UC
Output Uout
RM
The output Uout has a very low output impedance of typically
1 Ohm; it can drive capacitive loads of up to 100 nF directly.
Adding series resistance Rf of several tenths of Ohms allows
much larger capacitive loads Cf (higher than 1 µF). Empirical
evaluation may be necessary to obtain optimum results. The
minimum load resistance on Uout is 1 kOhm.
Uout
Uref
Rf
Cf
Figure 29: filtered Uout connection
Total Primary Resistance
The primary resistance is 0.72 mΩ per conductor.
In the following table, examples of primary resistance according
to the number of primary turns.
Number
Primary
of primary
nominal RMS
turns
current
NP
Output
voltage
Primary
resistance
Uout [V]
RP [mΩ]
Uref ±0.625
0.24
Recommended
connections
10
1
2
3
±IP N
±IP N/2
±IP N/3
Uref ±0.625
Uref ±0.625
9
8 OUT
IN 1
2
3
10
9
8 OUT
IN 1
10
2
9
3
8 OUT
IN 1
2
3
1.08
2.16
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LESR series
External reference voltage
The REF pin can be used either as a reference voltage output or as a reference voltage input.
When used in reference voltage output, the internal reference voltage Uref is used by the transducer as the reference point for
bipolar measurements.
The internal reference voltage output accuracy is defined in the electrical parameter data.
When used in reference voltage input, an external reference voltage is connected to the REF pin.
In this case, the maximun allowable reference voltage range is 0.5 V - 2.75 V.
The REF pin must be able to source or sink an input current of 1.5 mA maximum.
If the reference voltage is not used, the REF pin should be left unconnected.
The following graphs shows the Uref pin current versus forced external Uref.
50
120
40
100
30
80
60
20
40
0
¦
2.75 V
−10
20
0
¦
2.75 V
−20
−40
−20
−60
−30
−80
−40
−50
0.5
IP M (A)
IP M (A)
10
−100
1
1.5
2
Uref (V)
2.5
3
−120
0.5
1
1.5
2
Uref (V)
2.5
3
Figure 30: Measuring range versus external Uref LESR 6-NP
Figure 31: Measuring range versus external Uref LESR 15-NP
Upper limit: IP = −9.6 * Uref + 45.6
Lower limit: IP = −9.6 * Uref + 2.4
Upper limit: IP = −24 * Uref + 114
Lower limit: IP = −24 * Uref + 6
(Uref = 0.5 … 2.75 V)
(Uref = 0.5 … 2.75 V)
(Uref = 0.5 … 2.75 V)
(Uref = 0 … 2.75 V)
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LESR series
External reference voltage
200
130
110
150
90
70
100
50
50
10
¦
−10
2.75 V
IP M (A)
IP M (A)
30
−30
2.75 V
¦
0
−50
−50
−100
−70
−90
−150
−110
−130
0.5
1
1.5
2
Uref (V)
2.5
−200
0.5
3
1
1.5
2
Uref (V)
2.5
3
Figure 32: Measuring range versus external Uref LESR 25-NP
Figure 33: Measuring range versus external Uref LESR 50-NP
Upper limit: IP = −40 *Uref + 190
Upper limit: IP = 113
Lower limit: IP = −40 * Uref + 10
Upper limit: IP = 150
Lower limit: IP = −80 * Uref + 20
Lower limit: IP = −150
(Uref = 1.85 … 2.75 V)
(Uref = 0 …1.85 V)
(Uref = 0 … 2.75 V)
(Uref = 0 … 2.75 V)
(Uref = 0 … 2.125 V)
(Uref = 2.125 … 2.75 V)
Example with Uref = 1.65 V:
● The 6 A version has a measuring range from −13.44 A to +29.76 A
● The 15 A version has a measuring range from −33.6 A to +74.4 A
● The 25 A version has a measuring range from −56 A to +113 A
● The 50 A version has a measuring range from −112 A to +150 A
Example with Uref = 0.5 V:
● The 6 A version has a measuring range from −2.4 A to +40.8 A
● The 15 A version has a measuring range from −6 A to +102 A
● The 25 A version has a measuring range from −10 A to +113 A
● The 50 A version has a measuring range from −20 A to +150 A
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LESR series
PCB footprint
Assembly on PCB
● Recommended PCB hole diameter
1.3 mm for primary pin
0.8 mm for secondary pin
● Maximum PCB thickness
2.4 mm
● Wave soldering profile
No clean process only.
maximum 260 °C for 10 s
Safety
This transducer must be used in limited-energy secondary circuits according to IEC 61010-1.
This transducer must be used in electric/electronic equipment with respect to applicable standards and safety requirements in
accordance with the manufacturer’s operating instructions.
Caution, risk of electrical shock
When operating the transducer, certain parts of the module can carry hazardous voltage (e.g. primary busbar, power supply).
Ignoring this warning can lead to injury and/or cause serious damage.
This transducer is a build-in device, whose conducting parts must be inaccessible after installation. A protective housing or
additional shield could be used.
Main supply must be able to be disconnected.
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LESR series
Dimensions (in mm, general linear tolerance ±0.25 mm)
Connection
+UC
RM
Uout
Uref
Remark
● Installation of the transducer must be done, unless
otherwise specified on the datasheet, according to LEM
Transducer Generic Mounting Rules. Please refer to LEM
document N°ANE120504 available on our Web site:
https://www.lem.com/en/file/3137/download
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LESR series
Packaging information
Standard delivery in cardboard: L × W × H: 315 × 200 × 120 mm
Each carboard contains 200 parts, placed into 4 Polystyrene-made trays of 50 parts each one.
Both trays and carboard are ESD-compliant.
The typical weight of the cardboard is 2.5 Kg.
50 transducers per tray
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www.lem.com